1. Field of the Invention
The present invention relates to a novel lectin like protein substance, method of obtaining same and anti-tumor agent comprising the same as an effective ingredient. The substance is produced through a cultivation of an insect cell and more particularly a cell line established from flesh fly (Sarcophaga peregrina) embryo.
2. Related Arts
The term of "Lectin" is a general one meaning glycoproteins found in animals, plants and bacteria inclusive of virus, excepting those of products due to an immunoreaction and some of the lectins obtained from plants had been known for long to behave as a hemagglutinin.
Recently, however, various lectins have been found not only in the plants, but also in animals, and physical significance and characteristics thereof have occupied the attention in the pharmacological field, since some of them shows an agglutination specific not only to erythrocyte, but also leucocyte, cancer cell and the like (for instance, Jap. Pat. Appln. No. 212436/1983 corresponding to Jap. Unexamined Pat. Appln. Gazette No. 105621/1960).
The present inventor has also found a substance from one of insecta, Sarcophaga peregrina, which substance shows lectin like activities, activates a macropharge in vitro to produce a tumor killing substance and has been named as "Sarcophaga-Lectin" (Jap. Pat. Appln. Nos. 123298/1982, 94972/1983 and 66330/1984 which correspond to Jap. Unexamined Pat. Appln. Gazette Nos. 13730/1984, 222422/1984 and 209530/1985, respectively).
As anti-tumor agents, chemotherapeutic agents, immunotherapeutic agents and the like have been clinically employed now but those have a relatively high side effect and thus it is anxious for to develop other anti-tumor agents which have a higher safety.
While, the Sarcophaga-Lectin as referred to has been expected as one of high safety anti-tumor agents but has difficulties in its productivity inclusive of insurance of the raw material, isolation and purification.